Torsional vibration absorber system

Abstract

A system for absorbing torsional vibration in a shaft which is drivingly rotated about an axis and wherein the shaft is exposed to torsional disturbances which tend to cyclically increase and decrease the rotational speed of the shaft utilizes a body attachable to the shaft for rotating therewith as the shaft rotates about its axis of rotation and cylindrical rolling elements positioned within cavities disposed in the body. During operation of the system, the torsional disturbances induce pendulum-like motion of the cylindrical elements within the cavities in a manner which absorbs torsional vibration of the shaft. The cylindrical elements, the cavities and the torsional disturbances are related to one another in accordance with an equation which optimizes performance of the system and circumvents time-consuming trial and error techniques during design of the system. The system is particularly well-suited for absorbing torsional vibration in a shaft which is rotated about an axis in response to power pulses generated within an internal combustion engine.

I claim: 
     
       1. A system for absorbing torsional vibration in a shaft which is drivingly rotated about an axis and wherein the shaft is exposed to torsional disturbances which tend to cyclically increase and decrease the rotational speed of the shaft, the system comprising: means defining at least one elongated cavity for rotating with a rotating shaft as the shaft rotates about its axis of shaft rotation, the elongated cavity arranged in such a relation to the shaft so that the longitudinal axis of the cavity is substantially parallel with the axis of shaft rotation;   a rolling element positioned within the one elongated cavity so as to be free to roll forwardly and rearwardly with respect to the direction of rotation of the shaft along the interior wall of the one cavity in a pendulum action upon exposure of the shaft to torsional disturbances during rotation; and   wherein the rolling element is related to the one elongated cavity and to the torsional disturbances desired to be absorbed by the system in accordance with the equation:   N.sup.2 =r.sub.w.sup.2 r.sub.3 /[r.sub.g.sup.2 +r.sub.w.sup.2 ][r.sub.1 -r.sub.w ]        wherein N is within about ±15% of the number of torsional disturbances per revolution of the shaft, r w  is the radius of the rolling element, r g  is the radius of gyration of the rolling element, r 1  is the radius of the one cavity, and r 3  is the radial distance of the one cavity from the axis of rotation of the shaft.   
     
     
       2. The system as defined in claim 1 wherein N is within at least about ±5% of the number of torsional disturbances per revolution of the shaft desired to be absorbed. 
     
     
       3. The system as defined in claim 1 wherein N is at least as great as the number of torsional disturbances per revolution of the shaft desired to be absorbed. 
     
     
       4. The system as defined in claim 1 wherein there are at least two elongated cavities defined by the cavity-defining means, a rolling element is positioned within each cavity as aforesaid, and each rolling element is related to its corresponding cavity and to the torsional disturbances desired to be absorbed by the system in accordance with the aforesaid equation. 
     
     
       5. The system as defined in claim 4 wherein the cavities are regularly spaced about the axis of shaft rotation. 
     
     
       6. The system as defined in claim 1 wherein the cavity-defining means is provided by a body which is securable to the shaft with which the system is utilized. 
     
     
       7. The system as defined in claim 6 wherein the body is a first body and includes a plurality of apertures with which a second body is securable to the first body. 
     
     
       8. The system as defined in claim 7 wherein the number of cavities is an integer multiple of the number of apertures. 
     
     
       9. The system as defined in claim 1 wherein the surface-to-surface contact between the periphery of each rolling element and the walls of its corresponding cavity is relatively high to reduce any likelihood of slip therebetween as the element rolls along the cavity walls during operation of the system. 
     
     
       10. The system as defined in claim 1 wherein the shaft is driven about its axis in response to power pulses generated within the cylinders of an internal combustion engine and wherein the number of torsional disturbances desired to be absorbed corresponds with the number of power pulses per revolution of the engine. 
     
     
       11. A system for absorbing torsional vibration in a shaft which is drivingly rotated about an axis and wherein the shaft is exposed to torsional disturbances during rotation and wherein the disturbances are substantially regularly spaced throughout each revolution of the shaft, the system comprising: means defining at least one cavity of circular cross section for rotating with a rotating shaft as the shaft rotates about its axis of shaft rotation, the cavity being arranged in such a relation to the shaft so that its circular cross section is substantially normal to the axis of shaft rotation;   a cylindrical rolling element positioned within each cavity so as to be free to roll along the walls of its corresponding cavity in a pendulum action in response to the torsional disturbances to which the shaft is exposed; and   wherein the cylindrical rolling element is related to its corresponding cavity and to the torsional disturbances desired to be absorbed by the system in accordance with the equation:   N.sup.2 =r.sub.w.sup.2 r.sub.3 /[r.sub.g.sup.2 +r.sub.w.sup.2 ][r.sub.1 -r.sub.w ]        wherein N is within about ±15% of the number of torsional disturbances per revolution of the shaft, r w  is the radius of the rolling element, r g  is the radius of gyration of the rolling element, r 1  is the radius of the cavity, and r 3  is the radial distance of the cavity from the axis of rotation of the shaft.   
     
     
       12. A system for absorbing torsional vibration in an internal combustion engine having multiple cylinders and a shaft which rotates about an axis in response to power pulses generated within the engine cylinders and wherein the power pulses create torsional disturbances in the shaft which are substantially regularly spaced throughout each revolution of the shaft, the system comprising: means associated with the rotating shaft of the engine for defining an elongated cavity which rotates with the shaft about the axis of shaft rotation, the cavity being arranged in such a relation to the shaft that the longitudinal axis of the cavity is substantially parallel with the axis of shaft rotation;   a rolling element positioned within the elongated cavity so as to be free to roll forwardly and rearwardly with respect to the direction of rotation of the shaft along the interior wall of the cavity in a pendulum action in response to the torsional disturbances created in the shaft during the rotation thereof; and   wherein each rolling element is related to its corresponding cylindrical cavity and to the engine with which the system is used in accordance with the equation:   N.sup.2 =r.sub.w.sup.2 r.sub.3 /[r.sub.g.sup.2 +r.sub.w.sup.2 ][r.sub.1 -r.sub.w ]        wherein N is within about ±15% of the number of power pulses per revolution of the engine shaft, r w  is the radius of each rolling element, r g  is the radius of gyration of the element, r 1  is the radius of the cavity, and r 3  is the radial distance of the cavity from the axis of rotation of the shaft.   
     
     
       13. The system as defined in claim 12 wherein N is within at least about ±5% of the number of power pulses per revolution of the shaft. 
     
     
       14. The system as defined in claim 12 wherein N is at least as great as the number of torsional disturbances per revolution of the shaft. 
     
     
       15. The system as defined in claim 12 wherein the cavity-defining means defines at least two elongated cavities arranged about the shaft as aforesaid, a rolling element is positioned within each cavity so as to be free to roll along the wall of its corresponding cavity as aforesaid, and each rolling element is related to its corresponding cavity and to the torsional disturbances desired to be absorbed by the system in accordance with the aforesaid equation. 
     
     
       16. The system as defined in claim 15 wherein the cavities, are regularly spaced about the axis of shaft rotation. 
     
     
       17. The system as defined in claim 12 wherein the cavity-defining means is provided by a body which is securable to the shaft with which the system is utilized. 
     
     
       18. The system as defined in claim 17 wherein the body is a first body and includes a plurality of apertures with which a second body is securable to the first body. 
     
     
       19. The system as defined in claim 18 wherein the number of cavities is a integer multiple of the number of apertures. 
     
     
       20. The system as defined in claim 12 wherein the surface-to-surface contact between the periphery of the rolling element and the walls of the cavity is relatively high to reduce any likelihood of slip therebetween as the element rolls along the cavity walls during operation of the system.